The 12 Powerfoods are true to their name: They fuel your workout, ignite your metabolism, and fight disease.

ALMONDS & OTHER NUTS

Why You Need Them:
Crunch for crunch, almonds are one of the best sources of alpha-tocopherol vitamin E -- the form that's best absorbed by your body. That matters to your muscles because "vitamin E is a potent antioxidant that can help prevent free-radical damage after heavy workouts," says Jeff Volek, Ph.D. And the fewer hits taken from free radicals, the faster your muscles will recover from a workout and start growing.

Fast Fact:
A recent study published in the Journal of the American Medical Association found that those men who consumed the most vitamin E -- from food sources, not supplements -- had a 67 percent lower risk of Alzheimer's disease than those eating the least vitamin E.

BEANS & OTHER LEGUMES

Why You Need Them:
Black, lima, pinto, navy -- you pick it. They're all low in fat, and they're packed with protein, fiber, and iron -- nutrients crucial for building muscle and losing weight. Gastrointestinal disadvantages notwithstanding, they serve as one of the key members of the Abs Diet cabinet because of all their nutritional power. In fact, if you can replace a meat-heavy dish with a bean-heavy dish a couple of times a week, you'll be lopping a lot of saturated fat out of your diet and replacing it with higher amounts of fiber.

Fast Fact:
Researchers in Australia, Indonesia, and Sweden studied the diets of 400 elderly men and women, and found that those who ate the most leafy green vegetables and beans.

SPINACH & OTHER GREEN VEGETABLES

Why You Need Them:
These Powerfoods pack superpowers thanks to their high nutrient content -- vitamins including A, C, and K; folate; beta-carotene; minerals including calcium and magnesium; fiber; and antioxidants. They help neutralize age-advancing free radicals, and the fiber content helps fill you up without loading you up with calories.

Fast Fact:
One serving of spinach supplies nearly a full day's vitamin A and half of your vitamin C. It's also loaded with folate -- a vitamin that protects against heart disease, stroke, and colon cancer.

DAIRY

Why You Need It:
Dairy gets so much good press for strengthening bones that it garners little attention for all the other stuff it does, such as help you shed pounds. Low-fat yogurt, cheeses, and other dairy products can play a key role in your diet. Look to milk as your major source of calcium. Liquids take up lots of room in your stomach, so your brain gets the signal that you're full.

Fast Fact:
3 or more servings of dairy per day can slash your risk of heart disease.

INSTANT OATMEAL

Why You Need It:
Oatmeal is the Jessica Alba of your pantry: It's a perfect 10. You can eat it at breakfast to propel you through sluggish mornings, a couple of hours before a workout to feel fully energized by the time you hit the weights, or at night to avoid a late-night binge. Oatmeal contains soluble fiber, meaning that it attracts fluid and stays in your stomach longer than insoluble fiber (like vegetables). Soluble fiber is thought to reduce blood cholesterol by binding with digestive acids made from cholesterol and sending them out of your body.

Fast Fact:
A Penn State study also showed that oatmeal sustains your blood sugar levels longer than many other foods, which keeps your insulin levels stable and ensures you won't be ravenous for the few hours that follow.

EGGS

Why You Need Them:
The protein found in eggs has the highest "biological value" of protein -- a measure of how well it supports your body's protein need -- of any food. In other words, the protein in eggs is more effective at building muscle than protein from other sources, even milk and beef. Eggs also contain vitamin B12, which is necessary for fat breakdown. For a long time, eggs were considered pure evil, because just two eggs contain enough cholesterol to put you over your daily recommended value. However, more and more research shows that eating an egg or two a day will not raise your cholesterol levels.

Why You Need Them:
A classic muscle-building nutrient, protein is the base of any solid diet plan. Turkey breast is one of the leanest meats you'll find, and it packs nearly one-third of your daily requirements of niacin and vitamin B6. Dark meat, if you prefer, has lots of zinc and iron.

Fast Fact:
Mayo Clinic researchers studying the diets of two African tribes found that the tribe that ate fish frequently had leptin levels nearly five times lower than the tribe that primarily ate vegetables. Lower leptin levels are associated with higher metabolism and fat-burning.

PEANUT BUTTER

Why You Need It:
Yes, PB has its disadvantages: It's high in calories, and it doesn't go over well when you order it in four-star restaurants. But it's packed with those heart-healthy monounsaturated fats that can increase your body's production of testosterone, which can help your muscles grow and your fat melt.

Fast Fact:
Most "classic" peanut butters such as Jif and Skippy have added sugar and trans fats. Scan the aisle for all-natural butters with one ingredient: peanuts.

OLIVE OIL

Why You Need It:
Sure, you could oil up your chest and arms and strike a pose, but it works better if you eat the stuff. "The monounsaturated fat in olive oil appears to act as an anticatabolic nutrient," says Doug Kalman, R.D., director of nutrition at Miami Research Associates. In other words, it prevents muscle breakdown by lowering levels of a sinister cellular protein called tumor necrosis factor-a, which is linked with muscle wasting and weakness (kind of like watching The View).

Fast Fact:
While all olive oil is high in monounsaturated fats, try to use the extra-virgin variety whenever possible; it has a higher level of free-radical-fighting vitamin E than the less chaste stuff.

WHOLE GRAIN BREAD & CEREALS

Why You Need Them:
There's only so long a person can survive on an all-protein diet or an all-salad diet or an all-anything diet. You crave carbohydrates because your body needs them. The key is to eat the ones that have been the least processed -- carbs that still have all their heart-healthy, belly-busting fiber intact.

Fast Fact:
Sometimes, after refining away all the vitamins, fiber, and minerals from wheat, food companies add molasses to the bread, turning it brown, and label it "wheat bread." It's a trick! Truly nutritious breads and other products will say "whole-wheat" or "whole-grain."

EXTRA PROTEIN POWDER

vWhy You Need It:
Whole foods such as fruits and veggies are key, but if you add refined whey protein powder to your meal -- in a smoothie, for instance -- you may very well have created the most powerful fat-burning meal possible. Whey protein is a high-quality protein that contains essential amino acids that build muscle and burn fat. But it's especially effective because it has the highest amount of protein for the fewest number of calories, making it fat's kryptonite.

Fast Fact:
If you get sick of protein powder in your smoothies, have some ricotta cheese. Unlike most dairy products, ricotta is made from whey instead of milk curd.

RASPBERRIES & OTHER BERRIES

Why You Need Them:
Berries carry powerful levels of antioxidants: all-purpose compounds that help your body fight heart disease and cancer. The berries' flavonoids may also help your eyesight, balance, coordination, and short-term memory. One cup of raspberries packs 6 grams of fiber and more than half of your daily requirement of vitamin C.

Fast Fact:
Blueberries are also loaded with the soluble fiber that, like oatmeal, keeps you fuller longer. In fact, they're one of the most healthful foods you can eat. Blueberries beat out 39 other fruits and vegetables in the antioxidant power ratings.